UNIVERSITY  OF   CALIFORNIA    PUBLICATIONS 


COLLEGE  OF  AGRICULTURE 


BITY  OF  CAUFurWUfc 

BRANCH  OF  THE 
COLLEGE  Of  A6«:CULTDRf 

COPY  2 


AGRICULTURAL  EXPERIMENT  STATION 


THE  PURPLE  SCALE 


By  H.  J.  QUAYLE 


BULLETIN  No.  226 

(Berkeley,  Cal.) 


Fri 


1'^      SACRAMENTO 

IC$U.RD,SON       j'-     -      -       SUPERINTE£ 

I        1912   .      f 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPERIMENT    STATION    STAFF. 

E.  J.  Wickson,  M.A.,  Director  and  Horticulturist. 

E.  W.  Hilgard,  Ph.D.,  LL.D.,  Chemist   (Emeritus). 

W.  A.  Setchell,  Ph.D.,   Botanist 

Leroy  Anderson,  Ph.D.,  Dairy  Industry  and  Superintendent  University  Farm  Schools. 

M.  E.  Jaffa,  M.S.,  Nutrition  Expert. 

R.   H.   Loughridge,  Ph.D.,   Soil  Chemist  and  Physicist    (Emeritus). 

C.  W.  Woodworth,  M.S.,  Entomologist. 

Ralph  E.   Smith,  B.S.,   Plant  Pathologist  and   Superintendent  of   Southern  California 

Pathological  Laboratory  and  Experiment  Station. 
G.  W.   Shaw,  M.A.,  Ph.D.,  Experiment  Agronomist  and  Agricultural  Technologist,   in 

charge  of  Cereal  Stations. 

E.  W.  Major,  B.Agr.,  Animal  Industry. 

B.  A.  Etcheverry,  B.S.,  Irrigation  Expert. 

F.  T.  Bioletti,  B.S.,  Viticulturist. 

W.  T.  Clarke,  B.S.,  Assistant  Horticulturist  and  Superintendent  of  University  Exten- 
sion in  Agriculture. 

John  S.  Burd,  B.S.,  Chemist,  in  charge  of  Fertilizer  Control. 

J.  E.  Coit,  Ph.D.,  Assistant  Pomologist,  Plant  Disease  Laboratory,  Whittier. 

George  E.  Colby,  M.S.,  Chemist  (Fruits,  Waters,  and  Insecticides),  in  charge  of 
Chemical  Laboratory. 

H.  J.  Quayle,  M.S.,  Assistant  Entomologist,  Plant  Disease  Laboratory,  Whittier. 

H.  M.  Hall,  Ph.D.,  Assistant  Botanist. 

C.  M.  Haring,  D.V.M.,  Assistant  Veterinarian  and  Bacteriologist. 
E.  B.  Babcock,  B.S.,  Assistant  Agricultural  Education. 

W.  B.  Herms.  M.A.,  Assistant  Entomologist. 

J.  H.  Norton,  M.S.,  Assistant  Chemist,  in  charge  of  Citrus  Experiment  Station,  River- 
side. 
W.  T.  Horne,  B.S.,  Assistant  Plant  Pathologist. 
C.  B.  Lipman,  Ph.D.,  Soil  Chemist  and  Bacteriologist. 
R.  E.  Mansell,  Assistant  Horticulturist,  in  charge  of  Central  Station  grounds. 

A.  J.  Gaumnitz,  Assistant  Agronomist,  University  Farm,  Davis. 
N.  D.  Ingham,  B.S.,  Assistant  in  Sylviculture,  Santa  Monica. 

T.  F.  Hunt,  B.S.,  Assistant  Plant  Pathologist. 

P.  L.  McCreary,  B.S.,  Chemist  in  Fertilizer  Control. 

E.  H.   Hagemann,  Assistant  in  Dairying,   Davis. 

R.  M.  Roberts,  Farm  Manager,  University  Farm,  Davis. 

B.  S.  Brown,  B.S.A.,  Assistant  Horticulturist,  University  Farm,  Davis. 
J.  I.  Thompson,  B.S.,  Assistant  Animal  Industry,  Davis. 

J.  C.  Bridwell,  B.S.,  Assistant  Entomologist. 
L.  Bonnet,  Assistant  Viticulturist. 

F.  C.  H.  Flossfeder,  Assistant  in  Viticulture,  University  Farm,  Davis. 
P.  L.  Hibbard,  B.S.,  Assistant  Fertilizer  Control  Laboratory. 

F.  E.  Johnson,  B.L.,  M.S.,  Assistant  Soil  Chemist. 

C.  H.  McCharles,  M.S.,  Assistant  Agricultural  Chemical  Laboratory. 

B.  A.  Madson,  B.S.A.,  Assistant  Experimental  Agronomist. 
Howard  Phillips,  B.S.,  Assistant  Animal  Industry,  Davis. 

Walter  E.  Packard,  M.S.,  Field  Assistant  Imperial  Valley  Investigation,  El  Centro. 
L.  M.  Davis,  B.S.,  Assistant  in  Dairy  Husbandry,  University  Farm,  Davis. 
S.  S.  Rogers,  B.S.,  Assistant  Plant  Pathologist,  Plant  Disease  Laboratory,  Whittier. 
H.  A.  Ruehe,  B.S.A.,  Assistant  in  Dairy  Husbandry,  University  Farm,  Davis. 

C.  O.  Smith,  M.S.,  Assistant  Plant  Pathologist,  Plant  Disease  Laboratory,  Whittier. 

E.  H.  Smith,  M.S.,  Assistant  Plant  Pathologist. 

C.  L.  Roadhouse,  D.V.M.,  Assistant  in  Veterinary  Science. 

F.  M.  Hayes,  D.V.M.,  Assistant  Veterinarian. 

M.  E.  Stover,  B.S.,  Assistant  in  Agricultural  Chemical  Laboratory. 

W.  H.  Volck,  Field  Assistant  in  Entomology,  Watsonville. 

E.  L.  Morris,  Field  Assistant  in  Entomology,  San  Jose. 

E.  E.  Thomas,  B.S.,  Assistant  Chemist,  Plant  Disease  Laboratory,  Whittier. 

A.  B.  Shaw,  B.S.,  Assistant  in  Entomology. 

G.  P.  Gray,  M.S.,  Chemist  in  Insecticides. 

H.   D.   Young,   B.S.,   Assistant   in   Agricultural   Chemistry,    Plant   Disease   Laboratory, 

Whittier. 
A.  R.  Tyler,  B.S.,  Assistant  in  Plant  Pathology,   Plant  Disease  Laboratory.   Whittier. 
E.  W.  Rust,  A.B.,   Assistant  in  Entomology,   Plant  Disease  Laboratory,   Whittier. 
L.  T.  Sharp,  B.S.,  Assistant  in  Soils. 
W.  W.  Cruess,  B.S.,  Assistant  in  Zymology. 
J.  F.  Mitchell,  D.V.M.,  Assistant  in  Veterinary  Laboratory. 
W.  B.  Boys,  Assistant  Cerealist. 

Anna  M.  T^ute,  Scientific  Assistant,  United  States  Department  of  Agriculture. 
J.  C.  Roper,  Patron,  University  Forestry  Station,  Chico. 
E.   C.  Miller/  Foreman,   Forestry   Station,   Chico. 

D.  L.  Bunnell^  Secretary  to  Director. 


CONTENTS. 


Page. 

EARLY  HISTORY 319 

INTRODUCTION    INTO    CALIFORNIA 319 

DISTRIBUTION  _ 321 

Over  World 321 

In  California 321 

ECONOMIC   IMPORTANCE   323 

FOOD  PLANTS 325 

DESCRIPTION  OF  THE  STAGES 32G 

The  Egg 326 

The  Active  Larva 326 

The  Second  Stage  Male 326 

The  Propupa 328 

The  Pupa 328 

The  Adult  Male 328 

The  Adult  Female 328 

LIFE  HISTORY  AND  HABITS 330 

The  Egg 330 

The  Active  Larva 330 

Locomotion   330 

Settling 332 

Formation  of  the  Scale 333 

The  Process  of  Molting , 334 

Development 335 

Seasonal  History 336 

PARASITE 337 

Aspidiotiphagus  citrinus  Craw 337 

PREDACEOUS  ENEMIES 33S 

RELATED  SPECIES 338 

BIBLIOGRAPHY    330 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/purplescale226quay 


THE  PURPLE  SCALE. 

Lepidosaphes  beckii  Newm. 
By  H.  J.  Quayle. 


EARLY  HISTORY. 

The  purple  scale,  Lepidosaphes  beckii,  was  first  made  known  by  New- 
man in  an  account  appearing  in  the  English  publication  "The  Ento- 
mologist" in  Februrary,  1869. 1  In  August  of  the  same  year  Packard2  in 
this  country  gave  a  brief  description  of  the  same  insect,  calling  it 
Aspidiotus  citricola.  Newman  had  given  it  the  genus  name  Coccus, 
which  has  since  been  changed,  while  his  species'  name  beckii  still  stands. 
From  1870  to  1876  a  few  articles  appeared  on  this  insect  in  France  and 
Italy.  Glover  has  the  second  notice  of  its  occurrence  in  the  United 
States  in  the  United  States  Department  of  Agriculture  Year  Book 
for  1876.  He  stated  that  it  was  found  on  imported  lemons  in  Jackson- 
ville, Florida,  in  1857. 

The  description  of  this  insect  given  by  Packard  was  made  simply  from 
unpublished  figures  and,  of  course,  was  inadequate.  The  first  complete 
description  was  given  by  Comstock  in  his  1880  report,  but  he  adopted 
the  same  specific  name  as  that  given  by  Packard. 

Introduction  into  California. — The  purple  scale  seems  to  have  been 
introduced  into  California  directly  from  Florida  in  1888  or  1889.  In  the 
report  of  the  California  State  Board  of  Horticulture  for  1893  Alexander 
Craw  states  that  "four  years  ago  two  carloads  of  orange  trees  were 
received  in  this  State  from  Florida  and  planted  in  Los  Angeles  and 
San  Diego  counties  without  disinfection.  The  result  is  that  the  climate 
that  has  been  preached  us  by  importers  of  Florida  stock  as  unfavorable 
to  the  development  of  this  species  of  scale  has  proved  to  be  the  opposite, 
for  on  a  visit  to  the  above  counties  last  summer  I  was  shown  trees 
completely  covered  with  purple  scale. ' '  The  May  number  of  the  Rural 
Calif ornian  for  1889  was  largely  occupied  with  discussions  of  the  prob- 
able damage  which  would  result  from  the  importation  of  Florida 
scales,  among  which  the  purple  was  the  most  important.  Dr.  Riley, 
writing  in  Insect  Life  in  1889,  states  that  "we  have  received  a  number 
of  letters  from  California  asking  our  opinion  on  the  necessity  for  quaran- 
tine, and  have  replied  that  while  there  seems  reason  to  believe,  and  we 
are  inclined  to  believe,  from  the  evidence  at  hand,  that  the  scales  men- 

JThe  Entom.   IV,  p.   217    (1869). 

2Guide  to  the   Study  of  Insects,   p.   527    (1869). 


320 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


Bulletin  226] 


THE    PURPLE    SCALE. 


321 


tioned  will  not  flourish  in  certain  parts  of  southern  California,  like 
Riverside,  where  the  heat  and  dryness  are  great,  yet  it  will  be  unwise  to 
depend  too  much  on  the  limited  experience  of  the  past.  We  have, 
therefore,  reiterated  our  convictions  as  to  the  necessity  of  using  every 
precaution  to  prevent  their  introduction." 


Fig. 


-Map   showing  distribution  of  the  purple  scale  over  the  southern 
California  citrus  belt. 


DISTRIBUTION. 

Over  World. — The  purple  scale  is  widely  distributed  over  the  world, 
as  reference  to  the  map  will  indicate.  The  localities  as  represented  by 
the  +s  on  the  map  are  as  follows :  Europe,  Maderia,  West  Africa, 
Mauritius,  Ceylon,  Japan,  Australia,  Tasmania,  New  Zealand,  Fiji, 
Hawaiian  Islands,  Bermuda,  Java,  West  Indies,  Paraguay,  Florida, 
Louisiana,  Colorado,  and  California. 

The  Paraguay  locality  given  above  is  based  upon  material  received 
in  July.  1911.  Mr.  C.  F.  Mead  collected  some  orange  leaves  that  had  a 
sickly  appearance  from  Pirapo,  Paraguay,  and  sent  them  to  Professor 
Coit  of  this  station.  The  leaves  proved  to  be  infested  with  typical  purple 
scale.  Hitherto  there  have  been  no  published  records,  to  our  knowledge, 
of  this  scale  occurring  in  that  locality  or  even  on  the  continent  of 
South  America. 

In  California. — At  the  present  time  the  purple  scale  occurs  in  the 
following  counties  in   California :     San   Diego,   Los  Angeles,   Orange, 


322 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


Ventura,  and  Santa  Barbara.  It  does  not  occur,  thus  far  at  least,  in  the 
citrus  sections  of  the  San  Joaquin  and  Sacramento  valleys.  Neither 
does  it  occur  in  Riverside  or  San  Bernardino  counties.  From  its  distri- 
bution in  the  above  coast  counties  it  would  appear  that  it  thrives  best 
in  a  cooler  and  moister  climate,  and  in  this  respect  it  is  similar  to  the 


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Fig.   3. — Half  of  orange  tree  defoliated  by  purple  scale. 

black  scale.  But  the  fact  that  it  does  not  occur  in  the  warmer  and  drier 
locations  may  be  due  to  the  very  rigid  quarantine  that  has  prevailed 
against  this  scale  in  those  sections.  Its  present  eastern  limit,  or  distance 
from  the  coast,  is  in  the  eastern  part  of  Los  Angeles  County,  but  here 
the  climatic  conditions  approach  that  of  the  still  more  interior  sections 


Bulletin  22G]  THE  purple  SCALE.  323 

of  Redlands  and  Riverside,  so  that  there  are  no  well  defined  climatic 
zones,  and  therefore  it  is  not  improbable  that  the  purple  scale  would 
establish  itself  in  those  sections. 


ECONOMIC  IMPORTANCE. 

Considering  the  scales  of  the  whole  of  the  southern  California  citrus 
belt,  the  purple  is  probably  entitled  to  rank  as  the  third  most  important. 
Its  distribution  is  not  so  general  as  that  of  either  the  black,  red  or 
yellow,  but  where  it  does  occur  it  is  the  most  serious  of  them  all,  because 
it  yields  less  readily  to  treatment.  Where  this  scale  occurs  among 
others,  fumigation  work  is  directed  primarily  against  the  purple,  and 
usually  successful  treatment  against  it  readily  controls  the  red  or  black 
scales. 

The  purple  scale  infests  leaf,  branch  and  fruit,  often  becoming 
completely  incrusted  upon  these,  but  it  is  usually  only  a  portion  of  the 
tree  that  becomes  thus  infested.  The  lower  side  or  interior  of  the 
tree  is  where  the  insect  thrives  best,  and  here  it  is  that  the  injury  is 
most  evident.  We  have  never  seen  the  greater  part  of  a  citrus  tree 
actually  killed  by  this  scale,  but  a  goodly  portion  of  one  side  or  the 
lower  and  interior  branches  are  very  frequently  thus  killed.  The  scale 
causes  a  marked  yellowing  of  the  leaves  and  there  is  consequently  a 
heavy  dropping  so  that  many  of  the  branches  will  be  completely 
denuded. 

The  injury  is  due  directly  to  the  feeding,  as  is  the  case  with  the  red 
scale,  since  no  honeydew  is  excreted.  The  scales  on  the  ripening  fruit 
often  have  a  tendency  to  delay  the  coloring,  and  a  marked  green  spot 
will  be  seen  about  the  scale  while  the  rest  of  the  surface  is  yellow.  On 
account  of  their  firm  attachment  to  the  fruit  they  are  with  great 
difficulty  removed  therefrom,  so  that  the  ordinary  brushing  or  washing 
of  the  packing-house  has  little  effect  upon  them. 

The  economic  status  of  this  scale  is  due  largely  to  its  resistance  to 
such  treatments  as  fumigation  or  spraying.  It  is  not  a  particularly 
prolific  insect  for  the  maximum  number  of  eggs  will  not  exceed  eighty, 
and  there  are  not  more  than  three,  or  at  most  four,  generations  a  year. 
It  is  in  the  egg  stage  that  it  is  most  resistant  to  fumigation.  This  must 
be  largely  on  account  of  the  very  complete  protection  afforded  the 
eggs  by  the  secretion  of  the  ventral  scale,  wrhich  together  with  the  dorsal 
scale  completely  envelops  them.  The  only  opening  is  at  the  posterior 
tip  where  the  young  upon  hatching  emerge.  It  has  frequently  been 
noticed  that  in  cases  of  incomplete  fumigation  a  few  eggs  at  the  extreme 
tip  will  be  killed  by  the  gas  while  the  more  interior  and  better  protected 
ones  will  remain  unharmed. 


324 


UNIVERSITY    OF    CALIFORNIA — EXPERIMENT    STATION. 


Fig.   4. — Orange  leaf  infested  with  purple  scale.     x2. 


Bulletin  22G] 


THE    PURPLE    SCALE. 


325 


FOOD  PLANTS. 

Lepidosaphes  oeckii  is  essentially  a  citrus  fruit  scale,  and  while  it  may 
occur  on  several  other  plants,  it  is  restricted  as  a  pest  in  California 
entirely  to  the  different  varieties  of  citrus.     Fortunately,  it  does  not 


Fig.   5. — A  cluster  of  oranges  badly  infested  with  purple  scale. 

attack,  or  at  most  but  very  rarely,  any  of  the  common  trees  or  shrubs 
growing  in  the  vicinity  of  citrus  trees,  so  that  the  problem  of  treat- 
ment and  control  is  limited  to  the  commercial  grove. 

The  complete  list  of  food  plants  from  which  Lepidosaphes  beckii  has 
been  recorded  is  as  follows:  Orange,  lemon,  citron,  grape  fruit,  fig, 
olive,  croton,  oak,  Elaeagnus,  Banksia  integri folia,  Taxus  cuspidata, 
Cercidiphyllum  japonicum,  Pomaderris  apetala. 


326 


UNIVERSITY    OP    CALIFORNIA EXPERIMENT    STATION. 


Fig.   6. — Purple  scale  after  first  molt,  and  mature  female.     x90. 


DESCRIPTION  OF  THE  STAGES. 
The  egg  is  oval  in  shape  measuring  .25  mm.  long  and  .15  mm.  broad. 
The  color  is  pearly  white  with  the  surface  very  minutely  granulate. 

The  active  larva  is  a  flat,  oval-shaped  creature, 
white  in  color  with  the  posterior  tip  brown.  The 
total  length  is  .78  mm.  and  the  greatest  width  is 
.64  mm.  The  antennas  are  six  jointed,  the  first 
joint  broadest,  the  last  longest  and  distinctly 
annulate.  There  are  two  small  lobes  widely  sep- 
arated at  posterior  end,  and  near  each  of  these 
on  the  inner  side  is  a  spine  which  extends  beyond 
the  tip  of  the  lobes.  There  are  two  other  similar 
spines  beyond  the  lobes. 

The  second  stage  male  length  .8  mm.,  width 
.25  mm. ;  general  color  purple.  In  the  earlier 
part  of  this  stage  the  purple  pigment  is  confined 

Fig.   7. — Active  larva        ^  °  -mi 

of     purple     scale.      largely  to  the  anterior  lateral  margins.     1  he  rest 

x35. 


Bulletin  220] 


THE    PURPLE    SCALE. 


32f 


of  the  insect,  excepting  the  posterior  tip  which  is  brown,  is  white  in 
color.  There  are  no  distinct  eyes  at  this  time,  but  later  the  purple 
granules  coalesce  into  definite  areas  forming  the  two  pairs  of  eyes  which 
are  conspicuous  in  the  latter  part  of  the  stage.  The  dorsal  and  ventral 
eyes  are  connected  by  a  narrow  neck  so  that  they  are  continuous.     These 


Fig.  8. — Stages  of  the  purple  scale  male.  1.  Second  stage.  2.  Propupa  with 
exuvium  of  second  stage  still  adhering  to  tip  of  body.  3.  Propupa. 
4.   Pupa.      5.  Adult  male.      x40. 

are  very  dark  purple.  The  median  lobes  are  large  and  broad  at  base 
with  the  margin  serrate.  The  second  pair  of  lobes  which  are  not  con- 
spicuous are  strongly  notched  in  middle.  Two  long  tapering  plates 
occur  between  the  median  lobes  and  also  two  similar  in  size  and  shape 


328 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


between  the  first  and  second,  and  second  and  third  lobes.  Two  other 
similar  plates  or  spines  are  found  beyond  the  third  pair. 

The  propupa  is  purple  in  general  color  and  measures  .8  mm.  long  and 
.25  mm.  wide.  The  sheaths  enclosing  the  antennae  legs  and  wings  may 
be  distinguished,  but  they  are  closely  associated  with  the  body  and  are 
not  conspicuous.  The  pygidial  characters  have  disappeared  and  the 
posterior  end  is  now  truncate  with  no  evidence  of  the  style.  The  ventral 
eyes  are  large,  very  dark  purple  in  color,  and  lie  close  together.  The 
dorsal  eyes  are  smaller  and  farther  apart. 

The  pupa,  length  exclusive  of  style  .1  mm.,  width  .28  mm.  at  widest 
part,  which  is  near  posterior  end.  Color  purple.  Sheaths  of  the 
appendages  conspicuous  and  more  or  less  free  from  the  body.  Eyes 
purple,  the  ventral  pair  closer  together  than  the  dorsal. 

Adult  male,  length  exclusive  of  style  .58  mm.,  style  .21  mm.,  wing 
expanse  1.6  mm.,  antennae  10  jointed;  comparative  lengths  5,  5,  19,  23, 
22,  20,  20,  18,  20,  15.  General  color,  yellowish  with  purple  pigment  scat- 
tered about  with  most  at  anterior  end.  This  pigment  also  extends  into 
the  joints  of  the  antennae  excepting  the  last  two  joints.  The  thorax  is 
light  brown  with  a  darker  band  extending  between  the  wings. 


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Fig.   9. — Pygidium  of  adult  female  purple  scale.     xl60. 

The  adult  female  will  average  1.2  mm.  in  length  and  .7  mm.  in  width. 
On  the  lateral  margin,  beginning  at  the  anterior  end,  are  from  three  to 
four  broadly  rounded  extensions,  and  following  these  from  three  to 
four  pointed  protuberances,  all  excepting  the  most  anterior  having 
short,  blunt  spines  at  tip.  There  are  always  three  pairs  of  lobes  visible 
and  often  a  fourth.  The  median  lobes  are  broad  and  bluntly  pointed, 
with  more  or  less  indication  of  serrations.  The  second  pair  is  broad 
and  deeply  notched,   the   third  short   and  broad  with  serrated   edge. 

Fig.  10. — Purple  scale.  1.  Development  of  scale  covering.  xl3.  2.  The  beginning 
of  the  formation  of  the  scale  covering.  xl20.  3.  Male  and  female  scales,  showing 
comparative  size  and  shape.  x27.  4.  Dorsal  and  ventral  view.  5.  Two  stages  of 
larva  of  Aspidiotiphagus  citrinus  within  purple  scale.  6.  Pupa?  of  same  within 
scales.     7.   Exit  holes  of  A.  citrinus.     8.   Formation  of  covering  after  first  molt. 


Bulletin  22G] 


THE    PURPLE    SCALE. 


329 


Fig.   10. — See  opposite  page  for  legend. 


330 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


There  are  two  spine-like  plates  between  the  median  pair  between  the 
first  and  second,  and  second  and  third.  There  are  also  two  between 
the  third  and  what  might  be  called  the  fourth  pair,  which  show  dis- 
tinctly in  some  of  the  specimens.  Another  pair  of  these  spine-like 
plates  is  found  at  the  extreme  edge  of  the  segment.  The  spines  that  are 
conspicuous  are  two  on  each  of  the  median  lobes  and  one  at  the  incision 
of  the  second. 

LIFE  HISTORY  AND   HABITS. 

The  Egg. — The  eggs  of  the  purple  scale  are  protected,  not  only  on  the 
upper  side  of  the  scale  covering,  but  on  the  under  side,  by  a  lighter 
and  more  cottony  secretion,  so  that  thej^  are  practically  surrounded  on 
all  sides  excepting  at  the  posterior  end.  They  are  arranged  in  regular 
rows  and  standing  partly  on  end.  The  number  will  vary  from  forty  to 
eighty.  These  are  deposited  over  a  period  of  three  or  four  weeks.  The 
time  of  hatching  will  vary  from  fifteen  days  in  summer  to  three  weeks 
or  longer  in  the  winter  months.  Those  nearest  the  tip  are  the  oldest 
and  are  the  first  to  hatch.  As  the  quota  of  eggs  are  deposited,  the  insect 
diminishes  in  size  and  contracts  toward  the  anterior  end  of  the  scale, 
filling  the  space  thus  left  with  eggs. 


THE  ACTIVE  LARVA. 

The  active  larva  usually  wanders  about  over  the  plant  for  a  short 
time  before  settling.  This  period  will  vary  from  a  few  hours  to  two  or 
three  days,  the  majority  becoming  fixed  within  one  day  after  emerging 
from  the  parent  scale.  The  scales  upon  hatching  may  not  make  their 
way  from  beneath  the  scale  immediately,  expecially  if  the  weather  is 
cool.  But  not  many,  generally  not  more  than  two  or  three,  will  be 
found  hatched  and  not  yet  emerged. 

Locomotion. — The  rate  at  which  the  young  larva  will  crawl  over 
smooth  paper  varies  considerably,  according  to  the  temperature.  With 
a  temperature  of  64°  F.,  the  maximum  distance  traveled  during  a  two- 
hour  period  was  27 \  inches,  while  a  distance  of  111  inches  was  covered 
when  the  temperature  was  89°. 

Locomotion  of  Young  Purple  Scale. 


Number 
examined. 

Date. 

H\ 

Time. 

Tempera- 
ture. 

Distance. 

Average 
distance. 

1 

November  18. 

1910 

9:20-12:20  p.  m. 

64° 

9       inches 

1 

November  18, 

1910 

•9:20-12:20  p.  m. 

64° 

21       inches 

1 

November  18, 

1910 

9:20-12:20  p.  ra. 

64° 

27.50  inches 

19  inches 

9 

November    2, 
November    2 , 

1910 

9:30-11:30  p.  m. 
9:30-11:30  p.  m. 

68° 
68° 

28       inches 
37.75  inches 

2 

1910 

33  inches 

3 

July             21 , 

1910 

1:20-  3:20  p.  m. 

89° 

111       inches 

111  inches 

Bulletin  226] 


THE    PURPLE    SCALE. 


331 


Fig.  11. — Actual  tracings  of  the  movement  of  young  purple  scales  for  a 
two-hour  period;  reduced  7  times.  Above,  the  temperature  was  64°  and 
the  average  distance  covered  was  19  inches.  Below,  the  temperature  was 
89°  and  the  distance  covered  was  111  inches. 

2— bul226 


332 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


The  rate  and  distance  of  travel  noted  above  was  on  smooth  paper. 
The  conditions  were  thus  more  favorable  than  will  ever  be  likely  to 
obtain  in  nature.  Counting  the  maximum  length  of  life  as  an  active 
larva  when  deprived  of  food  at  four  days,  the  highest  possible  record 
under  the  most  favorable  conditions  would  be  a  total  of  444  feet.  But 
obstacles  to  travel,  such  as  a  pulverized  soil,  make  a  very  different  story. 

With  a  temperature  of  86°  at  9  a.  m.,  twenty-five  active  young  were 
placed  unharmed  in  the  center  of  an  area  of  sand,  having  a  five-inch 
radius.  None  reached  the  edge  during  the  same  day  or  the  day  fol- 
lowing. Another  similar  experiment  resulted  negatively.  A  third, 
similar  to  the  others,  was  started,  and  out  of  twenty-five  scales  liber- 
ated, one  reached  the  margin  in  5f  hours.  This  was  the  only  one  that 
succeeded  in  crossing  a  five-inch  strip  of  sand. 

The  following  records  were  made  on  a  three-inch  radius  of  sand : 


Number 
liberated. 

Temperature. 

Time. 

Results . 

20 
20 
10 

63°F 
82°  F 
65°  F 

1:30  p.  m. 
9:45  a.  m. 
9:30  a.  m. 

None  reached  margin 
2  out  at  12:30 
2  out  at  1  p.  m. 

Other  tests  were  made  with  orchard  soil,  but  there  seemed  to  be  little 
difference  over  that  of  sand.  It  will  thus  be  seen  that  the  young  purple 
scales  are  able  to  make  but  little  progress  over  soil  that  is  well  cultivated. 
Only  an  exceedingly  small  percentage  of  those  liberated  crossed  but 
three  or  five  inches  of  such  soil.  If  the  soil  is  compacted  as  after  heavy 
rains  or  in  irrigation  furrows  considerable  progress  may  be  made,  but 
even  here  the  factor  of  their  own  powers  of  locomotion  in  their  dis- 
tribution is  very  small. 

Settling. — Out  of  240  scales  liberated  in  leaf  cages  at  different  times 
from  March  to  September,  122  or  about  50  per  cent  became  established. 
This  should  represent  a  fair  average,  or,  if  anything,  an  under  estimate 
of  the  percentage,  since  the  young  were  liberated  on  suitable  leaves  and 
protected  from  all  outside  agencies.  There  seems  no  doubt  that  condi- 
tions as  they  ordinarily  obtain  in  nature  would  decrease  the  above 
percentage  considerably.  It  may,  therefore,  be  counted  that  at  least 
50  per  cent  of  the  scales  fail  to  become  established  even  under  the  most 
favorable  conditions. 

The  young  purple  scale  may  settle  either  on  the  branch,  leaf,  or  fruit. 
The  branches  or  leaves  are  the  first  to  become  infested,  but  if  they  are 
abundant  on  these,  the  fruit  in  the  vicinity  will  become  badly  infested 
also.  Where  the  numbers  are  not  large  there  is  a  tendency  for  the 
young  scales  to  settle  along  the  midrib  or  large  veins  of  the  leaf.  This 
tendency  was  usually  strongly  shown  in  our  breeding  cages.     They  do 


Bulletin  226]  THE  PURPLE  SCALE.  333 

not  migrate  far  from  the  parent  as  a  rule.  It  is  most  usual  to  find  this 
scale  limited  to  but  a  portion  of  the  tree,  and  while  this  portion  may  be 
so  severely  infested  as  to  be  killed,  the  rest  of  the  tree  may  be  in  a 
healthy  condition  and  comparatively  free  from  the  scale.  The  infested 
portion  is  nearly  always  on  the  lower  side  of  the  tree  and  later  extends 
upward  covering  the  greater  part  of  one  side  of  the  tree.  This  side  is 
not  necessarily  away  from  the  sun  for  it  has  been  noted  on  the  east, 
south  and  west  sides  of  the  trees. 

Formation  of  the  Scale. — Upon  settling,  the  young  larva  of  the  purple 
scale  very  soon  secretes  a  couple  of  rather  coarse  cottony  threads  from 
the  anterior  end  of  its  body,  apparently  from  just  under  the  margin 
of  the  anterior  end.  These  are  long  entangling  threads  that  extend 
entirely  over  and  around  the  insect.  The  function  of  these  is  undoubt- 
edly a  provision  for  protection  while  the  more  compact  covering  is 
being  secreted.  At  any  rate  these  entangling  threads  answer  this  pur- 
pose, for  it  has  been  many  times  observed  that  a  young  Coccinelid  larva 
upon  striking  them  will  immediately  back  away  or  turn  in  another  direc- 
tion without  molesting  the  insect  thus  protected.  These  entangling 
threads  remain  until  the  insect  is  about  half  grown,  and,  where  the 
young  scales  are  numerous,  they  form  a  fuzzy  coating  over  the  infested 
surface.  Some  practical  fumigators  use  this  as  a  criterion  that  the 
insect  is  in  the  best  stage  for  treatment;  and  this  is  correct,  for  such 
threads  are  lost  as  they  approach  maturity. 

After  these  two  long  protecting  threads  are  formed  the  insect  begins 
the  secretion  of  the  permanent  scale.  These  threads  are  very  much 
finer  than  the  first  ones  and  cover  the  insect  more  compactly.  The  cov- 
ering for  a  day  or  two  is  of  course  thin  enough  to  make  out  very 
readily  the  insect  beneath.  This  covering  is  started  at  the  posterior  end, 
and,  after  about  one  day,  only  the  anterior  one  fourth  of  the  insect  is 
free.  The  long,  entangling  threads  are  still  present  and  these  remain  for 
a  considerable  time.  Later,  however,  after  the  scales  are  about  one 
half  grown  they  are  lost.  After  the  covering  has  reached  the  anterior 
end  and  the  insect  is  completely  covered,  it  still  extends  the  covering 
in  two  horn-like  projections  as  shown  in  Figs.  10-12.  If  these  are  care- 
fully lifted  the  antennae  will  be  found  beneath  so  that  they  serve  as  a 
protection  to  the  antennae  for  a  time.  As  the  insect  grows  older,  the 
scale  becomes  more  compacted.  When  the  first  molt  occurs,  the  entire 
skin  is  incorporated  in  the  dorsal  scale.  The  insect  works  its  way  out 
beneath,  leaving  the  covering  which  has  been  secreted,  and  the  cast 
skin,  above  it.  Very  soon,  however,  the  scale  is  extended  posteriorly  so 
that  the  cast  skin  becomes  an  oval,  dark  brown  plate  at  the  anterior  tip 
of  the  scale.  The  second  cast  skin,  which  is  very  much  larger  than  the 
first,  is  also  incorporated  into  the  dorsal  scale  covering.  The  secretion 
is  continued  and  the  scale  extended  beyond  the  second  exuvium  until  the 


334 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


part  beyond  becomes  the  length  of  the  rest  of  the  covering.  As  the 
female  becomes  mature  and  egg  laying  begins,  a  considerable  secretion 
is  formed  on  the  under  side.  This  is  secreted  from  the  sides  of  the  insect, 
the  two  films  meeting  down  the  central  line.  A  narrow  strip  of  this 
ventral  scale  is  formed  on  either  side  of  the  scale  beneath  during  the 
earlier  stages,  particularly  at  the  anterior  end,  and  this  gradually 
widens  and  extends  more  posteriorly  as  the  insect  becomes  mature.  But 
no  part  of  the  cast  skins  are  found  in  this  ventral  scale  which  is  entirely 
the  secretion  of  the  insect. 

In  the  case  of  the  male  only  the  first  cast  skin  is  incorporated  into  the 
scale  covering.  This  is  exactly  similar  to  that  of  the  female,  since  there 
is  no  difference  in  the  sexes  until  after  the  first  molt.  But  all  succeeding 
cast  skins  of  the  male  are  pushed  back  and  from  beneath  the  scale 
covering.  The  narrow,  elongate  covering,  typical  of  the  male  insect,  is 
formed  entirely  during  the  second  stage  of  the  insect. 

The  Process  of  Molting. — In  the  case  of  the  purple  scale  the  molting 
process  is  very  different  from  that  of  Chrysomphalus  aurantii  and  also 

different  from  that  of  the  unarmored  scales  as 
represented  by  Saissetia  olece.  In  the  case  of 
the  red  scale,  the  rent  in  the  old  skin  occurs 
along  the  margin  of  the  body,  so  that  the  dorsal 
half  becomes  incorporated  in  the  dorsal  scale 
and  the  ventral  half  of  the  ventral  scale.  In 
Saissetia  olece,  Coccus  hesperidum,  and  others 
of  the  unarmored  group,  the  skin  is  split  at  the 
anterior  end  and  pushed  backward  and  entirely 
free  from  the  insect. 

The  rent  in  the  skin  of  the  purple  scale 
occurs  on  the  ventral  side  in  a  more  or  less 
irregular  line  a  short  distance  from  the  margin. 
At  the  anterior  end  this  is  between  the  rostrum 
and  the  antennas,  on  the  sides,  between  the  legs 
and  the  body  margin ;  and  at  the  posterior  end, 
just  anterior  to  the  pygidium.  The  insect  first 
emerges,  presumably  at  the  anterior  end  (the 
process  can  not  actually  be  observed)  and  later 
pulls  the  posterior  end  forward  and  downward, 
leaving  the  old  skin  directly  above  it.  From  the  appearance  of  the  cast 
skin  the  insect  could  very  readily,  simply  by  a  contraction  of  the  body, 
free  itself  from  the  narrow  projecting  portion  of  the  ventral  scale  at  the 
anterior  end.  In  the  case  of  the  posterior  end,  the  rent  does  not  occur 
so  near  the  margin,  hence  the  projecting  scale  is  somewhat  broader  than 
that  at  the  anterior  end.  But  once  the  anterior  end  of  the  insect  was 
free,  it  would  be  easy  to  liberate  itself  from  this  posterior  pocket.     That 


Fig.  12. — First  cast  skin  of 
purple  scale ;  ventral 
view,  showing  how  skin 
is  split  and  ventral  por- 
tion with  legs  and  mouth 
parts  pushed  back. 


Bulletin  22G]  the  purple  scale.  335 

the  anterior  end  is  first  freed  from  the  old  scale  is  further  shown  by  the 
fact  that  the  old  ventral  skin  is  pushed  backward,  which  would  not  be 
possible  in  any  other  case. 

The  exuvium,  therefore,  is  entirely  in  the  upper  or  dorsal  part  of  the 
scale  covering.  After  clearing  in  potash  it  will  be  seen  that  the  antennas 
are  intact  at  the  anterior  end,  the  rent  having  occurred  posterior  to 
them,  so  that  their  position  has  not  been  changed  in  the  molting  process. 
At  the  posterior  end  all  the  characters  of  the  pygidium  can  be  made  out 
as  clearly  as  in  the  perfect  insect,  for  these,  likewise,  have  not  been 
disturbed.  As  in  the  opposite  end  the  insect  has  simply  pulled  itself 
from  within,  leaving  all  the  characters  undisturbed.  The  ventral  por- 
tion of  the  molted  skin,  instead  of  being  simply  laid  down  beneath  the 
insect,  is  pushed  posteriorly  as  far  as  the  pygidium,  or  to  the  edge  of 
the  rent  at  the  posterior  end.  Here  the  legs  and  rostrum  may  be  made 
out,  the  whole  being  more  or  less  doubled  up  from  the  process  of  pushing 
backward  underneath  the  insect. 

Development. — The  first  molt  of  the  purple  scale  occurs  about  twenty- 
six  days  after  birth.  Up  to  this  period  there  is  no  difference  between 
the  sexes,  but  the  difference  becomes  sharply  marked  immediately  after 
this  stage.  In  the  case  of  the  female,  the  period  between  the  first  and 
second  molts  is  about  the  same  as  that  from  birth  to  the  first  molt.  The 
second  molt  brings  the  female  to  maturity,  at  least  so  far  as  the  molting 
is  concerned. 

Ten  or  twelve  days  after  the  first  molt,  the  male  undergoes  a  second 
molt,  bringing  it  to  the  propupal  stage.  This  stage  is  distinguished 
from  the  true  pupa  chiefly  by  the  less  fully  developed  appendages,  as 
shown  by  their  enclosing  sheaths.  After  eight  or  ten  days  in  this  stage, 
it  changes  to  the  true  pupal  condition,  and  a  similar  period  is  passed 
in  this  stage  before  emerging  as  an  adult.  The  male,  therefore,  issues 
as  an  adult  about  sixty  days  from  birth.  The  period  will  be  from  ten 
to  twelve  days  less  during  the  warmest  part  of  the  season,  and  extended 
as  much  as  twenty  or  twenty-five  days  in  winter. 

The  female  will  begin  depositing  eggs  about  seventy-five  days  from 
birth,  or  fifteen  days  after  fertilization  by  the  male.  Egg  laying  will 
continue  for  three  or  four  weeks.  The  eggs  hatch  and  young  will 
emerge  from  the  scale  on  an  average  of  three  months  from  birth;  this 
again  varying  from  ten  or  twelve  days  less  in  midsummer  to  a  month 
or  more  in  winter.  After  the  female  has  deposited  her  quota  of  eggs, 
numbering  from  thirty  to  eighty,  she  dies,  making  the  complete  life 
cvcle  from  four  months  in  summer  to  from  five  to  six  months  in  winter. 


336 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


Lepidosaphes 

beckii.     Development. 

Number 
examined. 

0 

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5-20-09 
5-20-09 
5-22-09 
5-22-09 
5-25-09 
6-25-09 
6-28-09 
7-  1-09 
7-  1-09 
7-19-09 
8-20-09 
8-21-09 
6-18-10 
6-18-10 
6-18-10 
6-18-10 
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3 
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6-10 

6-6 

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125... — 

6-10 

116 

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152 

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153 

6-18 
6-18 

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154 

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155 



162 

52 
37 
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28 
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305 

10-27 

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580 

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26  days 

4-17   -._ 

7-25 
50  days     36 

7-13 
days 

7-20  __ 
44 

52 

65 

75 

Summary  av 

90 

SEASONAL  HISTORY. 

Since  the  time  required  for  the  life  cycle,  from  young  to  young, 
during  the  summer  months  is  about  three  months  and  in  winter  may 
be  prolonged  a  month  or  more  longer,  the  number  of  generations  will 
not  exceed  four.  In  fact,  during  ordinary  seasons  there  will  be  but 
three  generations,  with  probably  a  partial  fourth.  From  May  to 
October,  inclusive,  they  will  go  through  their  development  in  three 
months,  or  slightly  less,  so  that  there  will  be  two  full  generations  dur- 
ing this  period.  A  third  will  get  fairly  well  started  before  the  colder 
wet  weather  of  January  and  February.  But  the  development  of  this 
generation  will  be  prolonged  by  the  lower  temperature  so  that  it  mayl 
require  four  months  for  the  cycle.  This  will  bring  it  into  March  again, 
when  at  best  the  fourth  generation  will  only  be  partially  developed  by 
the  last  of  April.  During  May,  and  also  in  June,  young  scales  begin 
appearing  in  large  numbers,  which  is  the  first  definite  spring  hatch. 
It  is  altogether  likely  that  in  many  cases  these  are  the  progeny  of  the 
third  generation.  During  the  remainder  of  the  summer  young  scales 
will  be  found  continuously  in  considerable  numbers.  Eggs  will  be 
found  at  any  season  of  the  year,  but  during  the  winter  months  the 
young  will  appear  mostly  during  the  warmer  periods. 


Bulletin  22G]  THE  purple  scale.  337 

PARASITE. 

Practically  nothing  has  been  written  about  any  parasites  of  the 
purple  scale  in  California.  This  scale  has  been  considered  to  be  freer 
from  parasites  than  any  of  the  other  citrus  fruit  scales.  While  this, 
in  general,  is  true,  yet  in  certain  places  the  purple  scale  is  as  heavily 
parasitized  as  the  red  or  yellow,  and  the  parasite  in  question  has  been 
known  to  occur  in  the  State  since  1891.  But  in  many  sections  of  the 
citrus  belt  where  the  purple  scale  occurs,  little  or  no  trace  of  this 
parasite  will  be  seen.  In  sections,  as  Whittier,  where  fumigation  is  so 
generally  practiced  as  it  was  in  1910  (98  per  cent  of  the  acreage) 
there  is  no  doubt  about  its  effect  on  the  parasites.  In  considerable 
purple  scale  material  collected  from  this  vicinity  during  the  past  two 
or  three  years,  there  have  been  but  occasional  instances  where  parasites 
were  obtained.  But  just  outside  the  Whittier  section,  where  trees 
infested  with  purple  scale  had  never  been  fumigated  or  sprayed,  as 
high  as  30  per  cent  or  40  per  cent  of  the  scales  at  one  time  were  found 
parasitized. 

This  same  fact  holds  true  for  the  yellow  scale  parasite,  for  it  is  the 
same  parasite  that  attacks  both  scales.  Yellow  scale  material  has  fre- 
quently been  obtained  from  sections  where  fumigation  is  generally  prac- 
ticed, but  none  or  few  parasites  were  secured.  But  yellow  scale  material 
taken  from  Santa  Barbara  County,  and  in  the  northern  sections  where 
no  fumigation  is  practiced,  had  a  considerable  percentage  of  the  scales 
parasitized  in  many  instances. 

Aspidiotiphagus  citrinus  Craw.* 

Aspidiotiphagus  citrinus  Craw,  is  the  only  parasite  that  we  have 
taken  thus  far  from  the  purple  scale.  This  is  the  insect  referred  to 
above,  and,  while  occurring  in  certain  limited  localities  in  considerable 
numbers,  it  is  not  common  throughout  the  purple  scale  belt.  This  is  a 
strictly  internal  parasite  and  attacks  the  scale  only  between  the  first 
and  second  molt.  The  scale  has  shed  its  first  skin  and  approaches  very 
nearly  the  time  when  it  should  cast  its  second  skin.  But  thus  far  no 
instance  has  been  observed  where  the  scale  had  actually  molted  the 
second  time. 

The  egg  is  deposited  within  the  insect  and  there  hatches  a  very 
minute,  white  larva,  with  a  tail-like  appendage.  This  is  afterward 
lost,  and  as  the  larva  becomes  mature  it  is  about  .85  mm.  long  and 
.35  mm.  wide,  tapering  slightly  toward  the  anterior  and  more  strongly 
toward  the  posterior  end.  It  pupates  within  the  scale,  the  pupa  at 
first  being  white  or  light  colored  but  later  turning  very  dark.  The  adult 
makes  its  way  out  through  a  circular  exit  hole  in  the  posterior  one  third 

♦For  a  more  detailed  account  of  this  parasite,  see  Cal.  Exp.  Sta.  Bull.  222. 


338  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 

of  the  scale,  these  being  found  only  in  the  partly  grown  scales.  The  age 
of  the  scale  when  grown  is  stopped  by  the  effects  of  the  parasite,  judg- 
ing entirely  from  the  condition  of  the  scale,  appears  to  be  about  forty 
or  forty-five  days,  when  the  second  molt  would  occur  in  about  fifty  or 
fifty-five  days.  During  the  past  two  years  a  large  number  of  these  para- 
sites have  been  found  issuing  in  December.  This  may  be  on  account  of 
the  fact  that  the  scales  are,  or  have  been,  in  the  proper  stage  for  attack. 

PREDACEOUS  ENEMIES. 

The  several  species  of  native  Coccinellidce,  together  with  the  larva  of 
Chrysopus  and  Hemerobius,  may  all  attack  the  purple  scale  as  well  as 
other  scale  insects.  But  the  one  Coccinelid  that  has  been  seen  most 
frequently  attacking  the  purple  scale  is  Rhizobius  lopantlice.  This 
species  also  occurs  commonly  on  the  red  scale.  The  larva  of  this  beetle 
is  distinguished  by  having  rectangular  areas  of  light  gray  on  the  other- 
wise dark  dorsal  surface.  When  full  grown  it  is  4  mm.  long  and  about 
1  mm.  wide.  The  adult  beetle  measures  from  2  to  2\  mm.  in  length, 
and  is  black  in  color  with  a  strong  metallic  luster. 

Scymnus  marginicollis  Mann,  is  another  species  that  is  often  found 
with  the  purple  scale.  This  beetle  is  similar  in  size  to  that  of  R.  lopan- 
thce,  but  is  of  a  dull  black  color  instead  of  the  metallic  bronze-like 
luster  of  that  of  lopanthce. 


RELATED  SPECIES. 

Aside  from  the  species  beckii,  there  are  three  others  recorded  from 
California  as  belonging  to  the  genus  Lepidosaphes.  These  are  L.  gloveru 
Pack.,  L.  idmi  Linn.,  and  L.  crawii  Ckll.  L.  crawii  has  been  recorded 
only  from  the  oak  and  Elceagnus,  and  is  therefore  of  no  economic 
importance.  L.  ulmi  is  the  common  and  widely  distributed  oyster-shell 
scale  and  occurs  on  many  deciduous  fruit  trees.  In  the  shape  and 
appearance  of  the  scale  covering,  it  closely  resembles  the  purple  scale, 
but  if  the  insect  itself  be  examined  it  is  readily  distinguished  by  the 
fact  that  the  lobes  are  not  serrate  as  in  the  case  with  L.  beckii, 
L.  gloverii  or  Glover's  scale  is  the  other  member  of  the  genus  that  \s 
primarily  a  citrus  fruit  scale.  It  has  been  only  rarely  met  with  in 
California,  while  in  Florida  it  is  of  very  common  occurrence.  This 
scale  covering  is  much  more  linear  in  shape  than  the  purple  and  is  not 
so  often  curved.  The  distinguishing  characters  of  the  insect  itself  are 
that  the  lobes  are  pointed  and  are  not  serrate. 


Bulletin  226]  THE  purple  SCALE.  339 


BIBLIOGRAPHY. 

The  following  is  the  bibliography  of  Lepidosaphes  beckii  that  has 
appeared  since  1903,  according  to  Mr.  E.  R.  Saccer  of  the  Bureau  of 
Entomology,  who  has  kindly  compiled  it  for  this  bulletin. 

Lepidosaphes   beckii    (Newn.). 

Theobald:     1st  Rep.  ec.  Ent.  Br.  Mus.  p.  133   (1903). 

Description,  hosts,  distribution  and  remedies. 

Marlatt,  C.  L. :     Can.  Ent.  XXXV,  p.  82  (1903). 

Simply    a    note. 

Coleman,  G.  A.:  Jn.  N.  Y.  Ent.  Soc.  XI,  p.  83  (June,  1903). 
Hempel,  A.:     Bol.  Agr.  Sao  Paulo,  V,  p.  322   (1904). 

Description,  host,  location,  etc. 

Sanders,  J.  G. :     Proc.  Ohio  Ac.  Sci.  IV  (2).  Sp.  papers  8,  p.  73  (1904).  fig.  41. 
Bibliography  and  description. 

Craw,  A. :  Rep.  Div.  Entom.  Hawaii  Bd.  Ag.  &  Forestry  Dec.  31,  1906.    pp.  143  and 

151. 
Editor:     Agric.   News.   West  Ind.,  V,  99.  p.  42    (1906). 

Del  Guercio:     Boll,  del  Min.  d'Agr.  Indust.  and  Comm.  V.  3,  p.  267   (1906)    (Fig). 
Description,  distribution,  etc. 

Kotinsky,  J.  :     Rep.  Div.  Entom.  Hawaii  for  yr.  ending  Dec.  31,  1905.  p.  139. 

Geoffroy,  A.:     L'Agricultura  Ligure  Anno  VI.  Feb.  15,  1906,  pp.. 51-52. 

Herrera,  A.  L. :  Bol.  d.  1.  Com.  de  Parasitologia  Agric.  Tomo.  Ill  No.  1,  pp.  189-92 

(1906). 
Draper,    W. :      Notes    of    the    Injurious    Scale    Insects    of    Mealy    Bugs    of    Egypt 

(Cairo),  1907.     p.   10. 

Green,  E.  E. :    Trans.  Linn.  Soc.  of  London,  vol.  XII.  Pt.  2.  Dec.  1907.  p.  203. 

Recorded  from  Seychelles,  Mauritius,  India,  Ceylon,  Japan,  Australia,  Tasmania, 
New  Zealand,  Fijii,  Hawaiian  Islands,  Java,  West  Indies,  United  States  of 
America,  Madeira,  Africa,  Europe. 

Ehrhorn,  E.  M.  :  2d  Bien.  Rep.  Com.  Hort.  State  of  Cal.     1905-06.     pp.  23  and  224. 
Hempel,  A. :  Consultas  attendidas  Bol.  da  Agr.  Estado  de  Sao  Paulo,  8  ser.  1907, 
p.   280. 
Merely  a  note. 

Lepidosaphes  beckii  (Newn.). 

Autran,  E.  :     Bol.  del  Min.  Agr.  vol.  VII.  No.  3.  p.  154.  1907. 

Carnes,  E.  K.  :     2d  Bien.  Rep.  Com.  Hort.  State  of  Cal.  1905-06  (1907),  pp.  217-18. 

Leonardi,  G. :     Estratto  dal  Bollettino  del  Laboratorio  di  Zoologia  generale  e  agraria 

della  R.  Scuola  Superiore  d'Agricoltura  in  Portici,  vol.  Ill,  July  15,  1908, 

pp.    190-91,    figs.   62-64. 
On  olives  in  Sicily. 

Howard,  C.  W.  :    Transval  Ag.  Jn.  vol.  VI,  No.  22,  Jan.  1908,  p.  271.     Fig. 

On  all  citrus  fruits  ;  also  fig.  croton,  and  oak. 
Ehrhorn,  E.  M.  :  Proc.  of  33d  Fruit  Grow.  Conv.  of  Cal.  p.  151.  Sacramento  (1908). 
Cook,  A.  J.:  Off.  Rep.  34th  Fruit  Grow.  Conv.  of  Cal.  p.  50.  Sacramento  (1908). 
Tower,  W.  V.:     Ann.  Rep.  P..R.  Agr.  Exp.  Sta.  p.  23.  San  Juan   (1908). 

On  orange  in  Porto  Rico. 
Newstead,  R.  :     R.  Quarterly  Jn.  Liverpool  Univ.  Vol.  Ill,  No.  6.  p.  12,  Jan.  1908. 

Cook,  M.  T.:     >  Estacion  Central  Agron.  de  Cuba,  Feb.  1908.  p.  22. 

Home,  W.  T.  :  S 

Common  in  Cuba. 

Marchal,  P.:     Mem.  Soc.  Zool.  France,  xxii,  1  and  2,  p.  181    (1909). 

3— bul226 


^40  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 

Aymes  and  Trabut:  Bui.  Agr.  de  Alg.  et  del  Tunisie,  xiv,  9,  pp.  222-223.  (1908).  Fig. 

Kirk.    T.    W.  :  ) 

Cockayne,   A.    H.  :  \  Am'  Rep'  N>  Z'  Dept-  Agr*  Div-  BioL  and  Hort  p"  283  (1909>- 

Essig,  E.  O. :     Bull.  No.  2.  Claremont  Pomological  Club.  Apr.  15,  1909. 

HaddeenWE.f' :   \°^  Ent-  xii'  S-  »  2"  <1009>- 

Carnes.  E.  K.  :  3d  Biennial  Kept.  Com.  Hort.  Cal.,  p.  25  (1909). 

Dean.  Geo.  A.:     Trans.  Kans.  Acad,  of  Sciences  XXII,  p.  275   (1909). 

Woodworth,  C.  W. :     Jn.  Econ.  Entom.  Vol.  II,  No.  5,  p.  359.  Oct.  1909. 

Barber,  T.  C.  :  Jn.  Econ.  Entom.  vol.  3,  No.  5,  p.  425.  Oct.  1910. 

Recorded    on    orange,    Citrus    trifoliata    and    Camellia    japonica    from    Audubon 
Park,  New  Orleans,  La. 


STATION    PUBLICATIONS  AVAILABLE   FOR   DISTRIBUTION. 


REPORTS. 

1896.  Report  of  the  Viticultural  Work  during  the  seasons  1S87-93,  with  data  regard- 
ing the  Vintages  of  1894-95. 

L897.  Resistant  Vines,  their  Selection,  Adaptation,  and  Grafting.  Appendix  to  Viti- 
cultural Report  for  189  6. 

1902.  Report  of  the  Agricultural  Experiment  Station  for  1898-1901. 

1903.  Report  of  the  Agricultural  Experiment  Station  for  1901-03. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for   1903-04. 


BULLETINS. 


Reprint. 

No.    128 

133 

147. 
149. 
153. 
159. 

162. 

165. 

167. 

168. 

169. 

170. 
171. 

172. 

174. 
176. 

177. 

178. 
179. 

180. 
181. 
182. 


183. 
184. 


1S5. 


186. 

187. 


188. 
189. 


190. 

191. 


Endurance  of  Drought  in  Soils  of 

the  Arid  Regions. 
Nature,  Value,  and  Utilization  of 
Alkali  Lands,  and  Tolerance  of 
Alkali.      (Revised  and  Reprint, 
1905.) 

Tolerance  of  Alkali  by  Various 
Cultures. 

Culture  work  of  the  Sub-stations. 

California  Sugar  Industry. 

Spraying  with  Distillates. 

Constribution  to  the  Study  of 
Fermentation. 

Commercial  Fertilizers.  (Dec.  1, 
1904.) 

Asparagus  and  Asparagus  Rust 
in  California. 

Manufacture  of  Dry  Wines  in 
Hot  Countries. 

Observations  on  Some  Vine  Dis- 
eases in  Sonoma  County. 

Tolerance  of  the  Sugar  Beet  for 
Alkali. 

Studies  in  Grasshopper  Control. 

Commercial  Fertilizers.  (June 
30,    1905.) 

Further  Experience  in  Asparagus 
Rust  Control. 

A  New  Wine-cooling  Machine. 

Sugar  Beets  in  the  San  Joaquin 
Valley. 

A  New  Method  of  Making  Dry 
Red  Wine. 

Mosquito  Control. 

Commercial  Fertilizers.  (June, 
1906.) 

Resistant  Vineyards. 

The  Selection  of  Seed-Wheat. 

Analysis  of  Paris  Green  and 
Lead  Arsenic.  Proposed  In- 
secticide Law. 

The  California  Tussock-moth. 

Report  of  the  Plant  Pathologist 
to  July  1,  1906. 

Report  of  Progress  in  Cereal  In- 
vestigations. 

The  Oidium  of  the  Vine. 

Commercial  Fertilizers.  (Janu- 
ary, 1907.) 

Lining  of  Ditches  and  Reservoirs 
to  Prevent  Seepage  and  Losses. 

Commercial  Fertilizers.  (June, 
1907.) 

The  Brown  Rot  of  the  Lemon. 

California  Peach  Blight. 


No.    192. 
193. 

194. 

195. 
197. 


198. 
199. 
200. 

201. 

202. 

203. 

204. 

205. 

206. 

207. 
208. 
209. 
210. 

211. 

212. 
213. 
214. 
215. 

216. 


217. 
218. 
219. 

220. 

221. 

222. 
223. 
224. 
225. 


Insects  Injurious  to  the  Vine  in 
California. 

The  Best  Wine  Grapes  for  Cali- 
fornia ;  Pruning  Young  Vines  ; 
Pruning  the  Sultanina. 

Commercial  Fertilizers.  (Dec, 
1907.) 

The  California  Grape  Root-worm. 

Grape  Culture  in  California  ;  Im- 
proved Methods  of  Wine-mak- 
ing;  Yeast  from  California 
Grapes. 

The  Grape  Leaf-Hopper. 

Bovine   Tuberculosis. 

Gum  Diseases  of  Citrus  Trees  in 
California. 

Commercial  Fertilizers.  (June, 
1908.) 

Commercial  Fertilizers.  (Decem- 
ber, 1908.) 

Report  of  the  Plant  Pathologist 
to  July  1,   1909. 

The  Dairy  Cow's  Record  and  the 
Stable. 

Commercial  Fertilizers.  (Decem- 
ber,  1909.) 

Commercial  Fertilizers.  (June, 
1910.) 

The  Control  of  the  Argentine  Ant. 

The  Late  Blight  of  Celery. 

The  Cream  Supply. 

Imperial  Valley  Settlers'  Crop 
Manual. 

How  to  Increase  the  Yield  of 
Wheat    in    California. 

California   White   Wheats. 

The   Principles   of  Wine-making. 

Citrus  Fruit  Insects. 

The  House  Fly  in  its  Relation  to 
Public  Health. 

A  Progress  Report  upon  Soil  and 
Climatic  Factors  Influencing 
the   Composition  of  Wheat. 

Honey  Plants  of  California. 

California  Plant  Diseases. 

Report  of  Live  Stock  Conditions 
In  Imperial  County,  California. 

Fumigation  Studies  No.  5  ;  Dos- 
age Tables. 

Commercial  Fertilizers  (Oct. 
1911). 

The  Red  or  Orange  Scale. 

The  Black  Scale. 

The  Production  of  the  Lima  Bean. 

Tolerance  of  Eucalyptus  for 
Alkali. 


CIRCULARS. 


No.        1.  Texas  Fever. 

7.  Remedies  for  Insects. 
9.  Asparagus  Rust. 

11.  Fumigation  Practice. 

12.  Silk  Culture. 

15.  Recent   Problems   in   Agriculture. 
What  a  University  Farm  is  For. 
19.  Disinfection  of  Stables. 

29.  Preliminary  Announcement  Con- 

cerning Instruction  in  Practical 
Agriculture  upon  the  Univer- 
sity Farm,  Davis,  Cal. 

30.  White  Fly  in  California. 

32.  White  Fly  Eradication. 

33.  Packing   Prunes   in   Cans.      Cane 

Sugar  vs.  Beet  Sugar. 

36.  Analyses  of  Fertilizers  for  Con- 
sumers. 

39.  Instruction  in  Practical  Agricul- 
ture at  the  University  Farm. 

46.  Suggestions  for  Garden  Work  in 
California  Schools. 

48.   Butter  Scoring  Contest,  1909. 

50.  Fumigation  Scheduling. 

52.  Information  for  Students  Con- 
cerning the  College  of  Agricul- 
ture. 


No. 


Some  Creamery  Problems  and 
Tests. 

Farmers'  Institutes  and  Univer- 
sity Extension  in  Agriculture. 

Experiments  with  Plants  and 
Soils  in  Laboratory,  Garden, 
and  Field. 

Butter  Scoring  Contest,  1910. 

University  Farm  School. 

The  School  Garden  in  the  Course 
of  Study. 

How  to  Make  an  Observation 
Hive. 

Announcement  of  Farmers'  Short 
Courses  for  1911. 

The  California  Insecticide  Law. 

Insecticides  and  Insect  Control. 

Development  of  Secondary 
School  Agriculture  in  Cali- 
fornia. 

The  Prevention   of  Hog  Cholera. 

The  Extermination  of  Morning- 
Glory. 

Observations  on  the  Status  of 
Corn-growing  in  California. 

Grains  Recommended  for  Trial. 


